1. Field of the Invention
The present invention is broadly concerned with improved slotter wheel apparatus of the type used in box making operations for the purpose of creating strategically located and sized slots in box blanks which in turn define the flap sections of an ultimate box. More particularly, it is concerned with such slotter wheel apparatus having dynamically retractable slotter blades permitting use of a given slotter wheel in the production of a wide variety of box blank sizes; in particular, the apparatus hereof permits retraction of slotter blades during rotation of the slotter wheel so that blanks of virtually any practical length can be formed on standard sized slotting machines. In addition, sectionalized, pivotally interconnected slotter blade constructions are described which in the cutting positions thereof extend through an arc greater than 180.degree., while nevertheless being fully retractable into a collapsed, folded-together orientation.
2. Description of the Prior Art
Conventional box making operations involve initially die cutting a box blank typically formed of corrugated board, followed by subjecting the blank to creasing and slotting steps in order to define the sides and end flaps of the blank. Generally speaking, the creasing and slotting operations are performed using adjacent, serially aligned creasing and slotting wheels respectively mounted upon powered shafts. As the blank is fed through the creasing/slotting device, the rotating creasing and slotting wheels act on the blank to create a series of spaced slot pairs of desired length separated by continuous creases. In this manner, the side panels of the final box are formed, along with the end closure flaps thereof. In order to efficiently produce blanks of varying dimensions, the slotting and creasing wheels may be shifted laterally along the lengths of their supporting shafts; moreover, cutting blades of varying lengths may be bolted to the slotting wheels at any one of a number of positions thereon, so that the size and location of the flap-defining slots may be altered.
While creasing/slotting devices of the type described are well known, they suffer from a serious drawback in that there are definite limitations as to the size of blanks which they may accommodate and process. That is, the maximum blank length which may be handled using a conventional slotter wheel is determined by the effective diameter of the wheel and knife blade. If it is desired to produce a larger blank, the only recourse is to employ a larger, more expensive slotting device. As will be appreciated, this problem stems from the fact that the slotter blade carried by conventional slotter wheel is fixed during rotation thereof and accordingly creates a corresponding slot during every wheel revolution.
U.S. Pat. No. 4,805,502 describes a slotter wheel device wherein the wheel-supporting shaft is equipped with an eccentric permitting selective movement of the supported slotting blades to a non-cutting position. However, the apparatus described in the '502 patent is incapable of moving a slotting blade between an extended slotting position and a retracted, blank-clearing position during rotation of the slotting wheel. In short, it is necessary to stop the operation of the wheel, manipulate the eccentric to alter the blade position, and then resume operations. Accordingly, the device described in this patent cannot accommodate oversized blanks and suffers from the same deficiencies as conventional slotters.